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MAN Energy Solutions

6G50ME-LGIM9.6

Name: MAN Energy Solutions 6G50ME-LGIM9.6
Brand: MAN Energy Solutions
SKU: OSE-38379

The MAN Energy Solutions 6G50ME‑LGIM9.6 is a six‑cylinder, low‑speed two‑stroke main engine delivering up to 18 600 kW at 127 rpm, notable for its Tier III compliance and dual‑fuel capability with methanol injection.

18600.0 kW

Power

Engine Specifications

Cylinders

500 mm

Bore

2300 mm

Stroke

18,600 kW

MCR Power

127.0 rpm

MCR RPM

2-stroke

Stroke Type

Family: MAN Energy Solutions ME-LGIM · Tier: Tier III · Fuel: HFO, VLSFO, MDO, Methanol

Inspector Detail

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Designation decoded

6-cylinder MAN G50ME-LGIM Mark 9.6 — Green Ultra-Long-Stroke two-stroke dual-fuel engine (methanol/diesel), bore 500 mm, stroke 2300 mm. LGIM = Liquid Gas Injection Methanol, liquid injection at 600–700 bar.

Background

The 6G50ME-LGIM9.6 is a Green Ultra-Long-Stroke engine with a 500 mm bore and a stroke-to-bore ratio of 4.600 — the highest in the LGIM program. This extreme stroke-to-bore ratio maximizes thermal efficiency but places particular demands on liner geometry, piston ring guidance and running-gear kinematics. The 6-cylinder configuration offers good vibration behaviour.

Calculated metrics

Stroke To Bore Ratio

4.6

Inspector checklist

Running Gear & Tribology

Liner wear particularly critical at S/B 4.6 — longest piston travel of all LGIM variants increases side forces
BN25 cylinder oil: check feed rate and distribution, cold corrosion during methanol operation
Piston rings: wear, running marks, blow-by — extreme S/B ratio produces the highest side pressures
Piston rod guide and crosshead: check increased side loading from the long stroke
Check piston crown for methanol combustion residues

Methanol Injection System (600–700 bar)

Check methanol injectors for tightness and corrosion — seal material compatibility critical
Verify injection pressure 600–700 bar — calibrate pressure sensors
Pilot diesel injectors: check atomization and timing
High-pressure methanol pumps: delivery rate and pressure stability
Check return lines and overpressure protection

Methanol Supply System

Check double-walled piping for leakage — flash point 12 °C
Methanol supply pumps: delivery rate sized for ~double the flow rate vs. HFO
Methanol quality: measure water content and contaminants
Check tank venting and inert gas supply

Safety Systems (Leak/Flame Detectors, Ventilation)

Function-test UV flame detectors — methanol flame almost invisible
Test leak detectors in double-wall piping and engine room
Trigger the ESD system completely and document response time
Check forced ventilation in methanol spaces for air change rate
Check PPE and eyewash stations — methanol TOXIC

Electronic Control

Check EICU software against current MAN Service Letters
Exhaust temperatures: 320–390 °C (methanol), 350–420 °C (diesel)
Test fuel changeover methanol↔diesel
Pay particular attention to cylinder pressure monitoring given the extreme S/B ratio

Logbook reference values

Parameter	Expected	Deviation means
Exhaust temperature (methanol operation)	320–390 °C	Deviations indicate injection or combustion problems
Exhaust temperature (diesel operation)	350–420 °C	Cylinder deviations >15 °C require injector inspection
Methanol injection pressure	600–700 bar	Pressure drop: wear; overpressure: control system fault
Cylinder oil feed rate (BN25)	0.6–1.2 g/kWh	Too low: cold corrosion and increased wear at S/B 4.6; too high: deposits
Liner temperature	50–80 °C (cooling water inlet)	Below 50 °C: acute risk of cold corrosion
Crankshaft deflection	Per MAN limits for the G50 crankshaft	Exceedance: bearing misalignment or foundation problems
Scavenge air pressure	2.0–3.5 bar (load-dependent)	Low pressure worsens methanol combustion

Common Failure Modes

Increased liner wear due to extreme S/B ratio

Symptoms: ['Accelerated wear compared to the S variant', 'Increased cylinder oil consumption', 'Rising blow-by']

Causes: S/B 4.6 produces the highest side forces of all LGIM engines, Insufficient cylinder oil lubrication on the long liner, Cold corrosion during methanol operation at low temperatures

Preventive: BN25 cylinder oil with optimized feed rate; liner temperature >50 °C; wear measurements at shortened intervals for S/B >4.5

Methanol injection valve leakage

Symptoms: ['Uneven exhaust temperatures', 'Methanol in the scavenge air duct', 'Rising consumption']

Causes: Seal degradation from methanol, Valve seat erosion, Corrosion from water in the methanol

Preventive: Regular leak testing; only approved materials; monitor water content

Piston ring failure under extreme stroke

Symptoms: ['Rising blow-by', 'Power loss', 'Increased oil consumption']

Causes: High side pressures at S/B 4.6 accelerate ring wear, Uneven cylinder oil distribution over the long stroke, Thermal deformation of the liner

Preventive: Check piston ring condition at every scavenge-port inspection; document wear rates and compare with MAN experience values

Pilot diesel injector failure

Symptoms: ['Misfires', 'Fallback to diesel', 'Rough engine running']

Causes: Coking at low pilot quantities, Needle valve wear, Timing drift

Preventive: Overhaul pilot injectors at shortened intervals; verify timing

Expert tips

💡 S/B 4.6 is the most extreme ratio in the entire LGIM program. The liner is correspondingly long, which complicates cylinder oil distribution over the full piston stroke. Feed rate and lubricating quill position are particularly critical here.
💡 The 6-cylinder G50 has good vibration behaviour — unlike 5-cylinder variants, torsional vibration is less critical here. Nevertheless, perform deflection measurements as scheduled.
💡 At S/B 4.6 and methanol operation, the combination of a long liner and cold-corrosion risk is particularly demanding — liner temperature management has the highest priority.

Related components

Methanol high-pressure pumps Double-wall piping system Flame and leak detectors (UV) Pilot diesel system ESD valves Cylinder oil dosing unit (BN25) Cylinder oil lubricating quills Crosshead bearings and guides Scavenge air blower Turbocharger

Classification & regulatory

SOLAS II-2, the IGF Code (MSC.391(95)) and MSC.1/Circ.1621 (Interim Guidelines for Methanol) apply. Observe classification society notations. Crew training on methanol hazards must be documented. Bunkering procedures per SGMF guidelines.

Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.